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A random sample of nine observations are drawn from the population, and we find the sample mean of these observations is x bar =17. What is the p value?
If McClellan, McNeil and Newhouse have available a variable representing the presence of a treatment that is effective but use equipment so expensive that only a few hospitals can afford it. Would t
Suppose we determine that an instrument in our regression is weak. Would using a polynomial in the first stage regression help? Discuss.
From past studies the publisher assumes the standard deviation is 2.5 minutes and that the population of times is normally distributed.
Use these data to construct a 95% confidence interval estimate of the true mean UTS for the sampled roll. What assumption you have assumed? Calculate and interpret a 95% prediction interval for a ne
Formulate and test the appropriate hypothesis. Assume population of paired differences has a normal distribution. Use the critical value approach.
At the 1% significance level, can it be concluded that there is a statistically significant difference in the proportions of men and women who rate slot machines as their favorite game? Formulate an
Does the recent sample allow the research firm to conclude that the mean apartment rental now exceeds $850 per month? Formulate and test the appropriate hypothesis using the p-vue approach. What is
Is the bottled water you drink safe? It has been suggested that about 10% of all bottled water violates at least one government standard. How large a sample of bottled water drinks should be selecte
Find an equation of the tangent plane and find symmetric equations of the normal line to the surface z=xy at the point (-2,-3,6).
Assume the samples come from normal populations with equal variances. At the 5% significance level, test the hypothesis that there is no difference in the mean weekly hours that executives in the t
Does the observed data contradict the company's claim? Formulate and test the appropriate hypotheses at the 2.5% level of significance. Use the critical value approach.
Suppose that the data yields (0.0804, 0.3176) for a confidence interval for the difference p1?p2 of the population proportions. What is the confidence level? (Give your answer in terms of percentage
Is there evidence, at a=0.07 level of significance, to conclude that there is a difference in proportions between first-years and fourth-years? Carry out an appropriate hypothesis test, filling in t
The air temperature was 33oF in the night and 66oF in the day. So in the day it was twice as warm as in the night. What's wrong with this statement?
A. Determine the sample size required to estimate a population proportion to within 0.032 with 97.8% confidence, assuming that you have no knowledge of the approximate value of the sample proportion
Suppose the distribution of Y, conditional on X = x, is N(x, x2), and marginal of X is U[0,1]. (a) Find Cov(X, Y)
The primary property of the alloys used for teeth filling is the percent of shrinkage on drying. For a certain alloy 45 test specimens showed an average shrinkage percentage of 18.4 and a variance of
Find the number of units that produces a maximum revenue. The revenue R is measured in dollars and x is the number of units produced.
Suppose you have data from an experiment with 3 levels of the independent variable. Explain why an ANOVA followed by post-hoc tests is superior to three t-tests for independent groups. (Hint: what t
Find an equation of the parabola that has the indicated vertex and whose graph passes through the given point. Vertex: (-3, -5); point: (-2, 0)
In a recent study of the effectiveness of popular diet plans, subjects were given a numerical score of how well they adhered to the diet, as well as having their weight loss measured.
Find an equation of the parabola that has the indicated vertex and whose graph passes through the given point. Vertex: (-5, 5); point: (-8, 4)
Give an example of one pair of these variables for which it does not make sense to calculate a correlation coefficient. Explain. Give an example of one pair of these variables for which it does makes